The present invention relates in general to dry cooling installations for coke, and in particular to a dry cooler of the type having an upright shaft for receiving coke to be cooled off, means for recirculating a cooling gas in the shaft, a dust separator for the gas stream and a waste heat boiler for utilizing the heat content of the gas.
In conventional dry cooling installations of the above described type, hot coke introduced into the cooling shaft is cooled down by a counterstream of a cooling gas which is introduced from below and flows upwardly through the coke. During this upward movement, the gas stream of necessity always entrains coke dust particles. Upon discharge from the shaft, the cooling gas stream usually passes through a waste heat boiler so as to transfer its heat content to the latter. It is desirable that the coke dust particles be separated before the gas stream enters the boiler, because if no dust removal is provided then the dust would precipitate on the boiler, thus causing wear ad clogging of heat-exchanging surfaces and impairing the conditions for the heat exchange.
It has already been devised to remove the dust from the hot cooling gas emanating from the cooling shaft by means of an impact separator, a gravity separator, or by a cyclone. This kind of separation is described, for example, in the German publication No. 24 55 496.
In this prior-art arrangement, the dust removing aggregates are spaced apart from the boiler. Consequently, the whole installation requires an additional space especially in the case of gravity separators. In addition, when in such known arrangements impact separators are used, the effectiveness of separation is unfavorably influenced by the fact that dust falling by gravity out of the gas stream is crossed and re-entrained by the latter. The application of cyclones for removing dust particles from hot gas streams having a temperature of about 800.degree. C. and supplied in large quantities (about 1500 cubic meters per ton of coke, whereby cubic meter is measured at 0.degree. C. and at a pressure of 1.013 bar) is limited from the economic point of view.